<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script>
			var a = {
				value: 0,
				toString: function() {
					return ++this.value;
				}
			}
			if (a == 1 && a == 2 && a == 3) {
				console.log(1);
			}
		</script>
	</body>
</html>
